Perhaps you should try some spelling variations:
"dios estudios peruanos." » "dios estudios americanos.", "dios estudios ensayos.", "dios estudios cervantinos.", "los estudios peruanos.", "otros estudios peruanos.", "altos estudios peruanos."
"tres estudioss urbano." » "tres estudios urbano.", "tres estudio urbano.", "tres estadios urbano.", "otros estudios urbano."
"dos estudios urbanos." » "los estudios urbanos."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("tres estudioss urbano.") or ((("dios estudios peruanos.") or ("dos estudios urbanos."))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tres estudioss urbano.") OR ((("dios estudios peruanos.") OR ("dos estudios urbanos."))))*.
• Removing quotes may allow a broader search: (( tres estudioss urbano. ) or ((( dios estudios peruanos. ) or ( dos estudios urbanos. ))))*.